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    <!--

    @license twgl.js Copyright (c) 2015, Gregg Tavares All Rights Reserved.
    Available via the MIT license.
    see: http://github.com/greggman/twgl.js for details

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    <meta property="og:title" content="TWGL.js - item list" />
    <meta property="og:type" content="website" />
    <meta property="og:image" content="http://twgljs.org/examples/screenshots/itemlist.png" />
    <meta property="og:description" content="TWGL.js - item list" />
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    <link href="/resources/images/twgljs-icon.png" rel="shortcut icon" type="image/png">

    <title>twgl.js - item list</title>
    <style>
      * {
          box-sizing: border-box;
          -moz-box-sizing: border-box;
      }
      body {
          margin: 0;
          font-family: monospace;
      }
      canvas {
          position: absolute;
          display: block;
          top: 0;
          width: 100vw;
          height: 100vh;
      }
      #outer {
          width: 100%;
          z-index: 2;
          position: absolute;
          top: 0px;
      }
      #content {
          margin: auto;
          padding: 2em;
      }
      #b {
        width: 100%;
        text-align: center;
      }
      .list-item {
          margin: 1em;
          padding: 1em;
          border: 1px solid #ccc;
          display: inline-block;
          width: 400px;
      }
      .list-item .view {
          width: 200px;
          height: 200px;
          float: left;
          margin: 0 1em 1em 0;
      }
      .list-item .description {
          font-family: sans-serif;
          font-size: small;
      }

      @media only screen and (max-width : 600px) {
          #content {
              padding: 0.5em;
          }
          .list-item {
              width: 90%;
              margin: 1em;
              padding: 0.5em;
          }
          .list-item .view {
              width: 150px;
              height: 150px;
          }
          .list-item .description {
              padding-left: 0em;
          }
      }

    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
    <div id="outer">
      <div id="content">
        <div id="b"><a href="http://twgljs.org">twgl.js</a> - item list</div>
        <div id="list"></div>
      </div>
    </div>
  </body>
  <script id="list-item-template" type="notjs">
    <div class="view"></div>
    <div class="description">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec eget enim mauris. In quis orci augue. Suspendisse aliquam enim non sem scelerisque pulvinar. Vestibulum elementum rhoncus tortor, a dapibus massa maximus vel. Praesent feugiat rutrum est a feugiat. Nam quis metus in arcu hendrerit molestie. Donec tempor purus id egestas convallis. Etiam libero nulla, gravida a eros at, blandit varius risus. Vivamus ut dui mi.</div>
  </script>
  <script id="vs" type="notjs">
uniform mat4 u_worldViewProjection;
uniform vec3 u_lightWorldPos;
uniform mat4 u_world;
uniform mat4 u_viewInverse;
uniform mat4 u_worldInverseTranspose;

attribute vec4 a_position;
attribute vec3 a_normal;
attribute vec2 a_texcoord;

varying vec4 v_position;
varying vec2 v_texCoord;
varying vec3 v_normal;
varying vec3 v_surfaceToLight;
varying vec3 v_surfaceToView;

void main() {
  v_texCoord = a_texcoord;
  v_position = (u_worldViewProjection * a_position);
  v_normal = (u_worldInverseTranspose * vec4(a_normal, 0)).xyz;
  v_surfaceToLight = u_lightWorldPos - (u_world * a_position).xyz;
  v_surfaceToView = (u_viewInverse[3] - (u_world * a_position)).xyz;
  gl_Position = v_position;
}
  </script>
  <script id="fs" type="notjs">
precision mediump float;

varying vec4 v_position;
varying vec2 v_texCoord;
varying vec3 v_normal;
varying vec3 v_surfaceToLight;
varying vec3 v_surfaceToView;

uniform vec4 u_lightColor;
uniform vec4 u_diffuseMult;
uniform sampler2D u_diffuse;
uniform vec4 u_specular;
uniform float u_shininess;
uniform float u_specularFactor;

vec4 lit(float l ,float h, float m) {
  return vec4(1.0,
              abs(l),//max(l, 0.0),
              (l > 0.0) ? pow(max(0.0, h), m) : 0.0,
              1.0);
}

void main() {
  vec4 diffuseColor = texture2D(u_diffuse, v_texCoord) * u_diffuseMult;
  vec3 a_normal = normalize(v_normal);
  vec3 surfaceToLight = normalize(v_surfaceToLight);
  vec3 surfaceToView = normalize(v_surfaceToView);
  vec3 halfVector = normalize(surfaceToLight + surfaceToView);
  vec4 litR = lit(dot(a_normal, surfaceToLight),
                    dot(a_normal, halfVector), u_shininess);
  vec4 outColor = vec4((
  u_lightColor * (diffuseColor * litR.y +
                u_specular * litR.z * u_specularFactor)).rgb,
      diffuseColor.a);
  gl_FragColor = outColor;
}
  </script>
  <script src="../dist/4.x/twgl-full.min.js"></script>
  <script src="../3rdparty/chroma.min.js"></script>
  <script>
    "use strict";
    twgl.setDefaults({attribPrefix: "a_"});
    const m4 = twgl.m4;
    const gl = document.querySelector("#c").getContext("webgl");
    const programInfo = twgl.createProgramInfo(gl, ["vs", "fs"]);

    const shapes = [
      twgl.primitives.createCubeBufferInfo(gl, 2),
      twgl.primitives.createSphereBufferInfo(gl, 1, 24, 12),
      twgl.primitives.createPlaneBufferInfo(gl, 2, 2),
      twgl.primitives.createTruncatedConeBufferInfo(gl, 1, 0, 2, 24, 1),
      twgl.primitives.createCresentBufferInfo(gl, 1, 1, 0.5, 0.1, 24),
      twgl.primitives.createCylinderBufferInfo(gl, 1, 2, 24, 2),
      twgl.primitives.createDiscBufferInfo(gl, 1, 24),
      twgl.primitives.createTorusBufferInfo(gl, 1, 0.4, 24, 12),
    ];

    function rand(min, max) {
      return min + Math.random() * (max - min);
    }

    // Shared values
    const lightWorldPosition = [1, 8, -10];
    const lightColor = [1, 1, 1, 1];
    const camera = m4.identity();
    const view = m4.identity();
    const viewProjection = m4.identity();

    const tex = twgl.createTexture(gl, {
      min: gl.NEAREST,
      mag: gl.NEAREST,
      src: [
        255, 255, 255, 255,
        192, 192, 192, 255,
        192, 192, 192, 255,
        255, 255, 255, 255,
      ],
    });

    const objects = [];
    const numObjects = 100;
    const list = document.getElementById("list");
    const listItemTemplate = document.getElementById("list-item-template").text;
    for (let ii = 0; ii < numObjects; ++ii) {
      const listElement = document.createElement("div");
      listElement.innerHTML = listItemTemplate;
      listElement.className = "list-item";
      const viewElement = listElement.querySelector(".view");
      const uniforms = {
        u_lightWorldPos: lightWorldPosition,
        u_lightColor: lightColor,
        u_diffuseMult: chroma.hsv(rand(0, 360), 0.4, 0.8).gl(),
        u_specular: [1, 1, 1, 1],
        u_shininess: 50,
        u_specularFactor: 1,
        u_diffuse: tex,
        u_viewInverse: camera,
        u_world: m4.identity(),
        u_worldInverseTranspose: m4.identity(),
        u_worldViewProjection: m4.identity(),
      };
      objects.push({
        ySpeed: rand(0.1, 0.3),
        zSpeed: rand(0.1, 0.3),
        uniforms: uniforms,
        viewElement: viewElement,
        programInfo: programInfo,
        bufferInfo: shapes[ii % shapes.length],
      });
      list.appendChild(listElement);
    }

    function render(time) {
      time *= 0.001;
      twgl.resizeCanvasToDisplaySize(gl.canvas);

      gl.enable(gl.DEPTH_TEST);
      gl.disable(gl.SCISSOR_TEST);
      gl.clearColor(0, 0, 0, 0);
      gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

      gl.enable(gl.SCISSOR_TEST);
      gl.clearColor(0.8, 0.8, 0.8, 1);

      const eye = [0, 0, -8];
      const target = [0, 0, 0];
      const up = [0, 1, 0];

      gl.canvas.style.transform = `translateY(${window.scrollY}px)`;

      m4.lookAt(eye, target, up, camera);
      m4.inverse(camera, view);

      objects.forEach(function(obj) {
        const viewElement = obj.viewElement;
        // get viewElement's position
        const rect = viewElement.getBoundingClientRect();
        if (rect.bottom < 0 || rect.top  > gl.canvas.clientHeight ||
            rect.right  < 0 || rect.left > gl.canvas.clientWidth) {
          return;  // it's off screen
        }

        const width  = rect.right - rect.left;
        const height = rect.bottom - rect.top;
        const left   = rect.left;
        const bottom = gl.canvas.clientHeight - rect.bottom - 1;

        gl.viewport(left, bottom, width, height);
        gl.scissor(left, bottom, width, height);
        gl.clear(gl.COLOR_BUFFER_BIT);

        const projection = m4.perspective(30 * Math.PI / 180, width / height, 0.5, 100);
        m4.multiply(projection, view, viewProjection);

        const uni = obj.uniforms;
        const world = uni.u_world;
        m4.identity(world);
        m4.rotateY(world, time * obj.ySpeed, world);
        m4.rotateZ(world, time * obj.zSpeed, world);
        m4.transpose(m4.inverse(world, uni.u_worldInverseTranspose), uni.u_worldInverseTranspose);
        m4.multiply(viewProjection, uni.u_world, uni.u_worldViewProjection);

        gl.useProgram(obj.programInfo.program);
        twgl.setBuffersAndAttributes(gl, obj.programInfo, obj.bufferInfo);
        twgl.setUniforms(obj.programInfo, uni);
        twgl.drawBufferInfo(gl, obj.bufferInfo);
      });
    }

    const animated = true;
    let requestId;
    if (animated) {
        const renderContinuously = function(time) {
            render(time);
            requestAnimationFrame(renderContinuously);
        };
        requestAnimationFrame(renderContinuously);
    } else {
        const renderRequest = function(time) {
            render(time);
            requestId = undefined;
        };
        // If animated
        const queueRender = function() {
            if (!requestId) {
              requestId = requestAnimationFrame(renderRequest);
            }
        };

        window.addEventListener('resize', queueRender);
        window.addEventListener('scroll', queueRender);

        queueRender();
    }

  </script>
</html>



